<!doctype html>
<html lang="en">
	<head>
		<!--  meta tags -->
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
		<!-- Bootstrap CSS -->
		<link rel="stylesheet" href="css/bootstrap.css">
		<style>
			div {
				border: 1px solid;
			}
		</style>
	</head>
	<body>
		<div class="container">
			<div class="row">
				<div class="col-8">
					col-8
					<div class="row">
						<div class="col-8 col-md-6">
							嵌套层: .col-8 .col-md-6
						</div>
						<div class="col-4 col-md-6">
							嵌套层: .col-4 .col-md-6
						</div>
					</div>
				</div>
			</div>
			<div class="row">
				<div class="col-lg-9">
					.col-lg-9
					<div class="row">
						<div class="col col-md-4">
							嵌套层: .col .col-md-4
						</div>
						<div class="col col-md-8">
							嵌套层: .col .col-md-8
						</div>
					</div>
				</div>
			</div>
		</div>

	</body>
</html>
